Reduction gear

Abstract

A reduction gear W1 that is configured to reduce a rotation speed input to an input shaft 1, and output the reduced rotation speed from an output shaft, the reduction gear including: an inner trochoid 8 that has a wavy curved surface formed on an inner circumferential side surface thereof; an inner trochoid holder 9 that is designed to hold the inner trochoid 8; an outer trochoid 3 that has a wavy curved surface formed on an outer circumferential side surface thereof; a rotation restriction unit that is designed to restrict rotation of the outer trochoid 3 around an axis thereof; and an output pin 9 that is pinched between the outer circumferential side surface of the outer trochoid 3 and the inner circumferential side surface of the inner trochoid 8.

The invention claimed is: 
     
       1. A reduction gear that is configured to reduce a rotation speed input from an input shaft provided with an eccentric portion, and output the reduced rotation speed to an output shaft, the reduction gear comprising:
 an outer trochoid that has a substantially tubular shape penetrating at both ends thereof and has a wavy curved surface formed on an outer circumferential side surface thereof; 
 a rotation restriction unit that is designed to restrict rotation of the outer trochoid around an axis thereof; and 
 an output pin that is held by the outer trochoid while being in contact with the outer circumferential side surface of the outer trochoid, wherein 
 the outer trochoid is connected to the eccentric portion of the input shaft and, when the input shaft rotates, the outer trochoid receives eccentric input from the input shaft and at the same time the rotation around the axis thereof is restricted by the rotation restriction unit, which makes the outer trochoid only revolve around an axis of rotation of the input shaft, and 
 the output pin has one end secured to the output shaft and, in response to the outer trochoid's revolution around the axis of rotation of the input shaft, the output pin is made to revolve around the axis of the input shaft in the same direction as the direction of rotation of the input shaft while being in contact with the outer circumferential surface of the outer trochoid to thereby rotate the output shaft in the same direction as the direction of rotation of the input shaft, and 
 wherein a ring-shaped part that is designed to be in contact with the output pin is provided at a position on one side of the output pin opposite to a side where the output pin is in contact with the outer circumferential side surface of the outer trochoid, and the output pin is pinched between the outer circumferential side surface of the outer trochoid and an inner circumferential side surface of the ring-shaped member.